Scale



Feb. 9 1926.

1,. G. KNAPP SCALE Filed Dec. 15, 1924 2 Sheets-Sheet 1 L. G. KNAPP SCALE Feb. 9 1926. 1,572,609

Filed Dec. 15, 1924 2 Sheets-Sheet 2 Le/ma G 6%? Patented Feb. 9, 1925.

UNITED STATES PATENT OFFICE.

LELAND G. KNAPP, OF CHICAGO, ILLINQIS, ASSIGNOB TO MONTGOMERY, WARD 86 00.,

0F CHICAGO, ILLINC'IS, A. CGBPORATIUN OF ILLENOIS.

SCALE.

Application filed December '1 0 all whom it may concern:

Be it known that I, LELAND G. Kimrr, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in a Scale; and I do here by declare the following to he a. full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to weighing-scales of the general. class in which an elevated platform is supported by a pair of levers affording a parallel motion and in which the weight is indicated by a pointer moved through a connection with one of the levers. Generally speaking, my invention aims to provide features of construction which will simplify the manufacture and assembling of such a scale and which will permit the avoiding of undesirable lost motion in a construction of unusually low cost.

Referring, to some of its more particular objects, my invention. provides novel means for connecting the platformsupport to the supporting stem in a simple manner which will eliminate all rocking movement while avoiding extensive machine work. it also aims to provide a novel arrangement of the platform-supporting stem and of the parallel pivoting levers, whereby lost motion between these parts can be avoided without requiring accurate or extensive machining of the several parts.

In a further object, my invention provides ascale construction in which the platformsupporting stem, the parallel levers, the ten sion spring and the rack bar can all be operatively connected before the resulting assembly is inserted in the casing; provides simple means for securing this assembly to the casing; and also provides simple means for preventing an accidental loosening of the screws which secure the said assembly to the casing. llloreovcr, my invention provides a. novel. and exceedingly inexpensive rack bar construction which will pcri'nit the rack bar to he punched out of sheet metal, and also provides simple means for preventing such a thin rack bar from jamming between. the pinion and adjacent wall portions.

Still further and also more detailed objects will appear rom the f ll vmg rccifiani n 15, 1924. Serial NO. 755,984.

and froin'the accompanying drawings, in which Fig. l is a central, vertical and longitudinal section through a scale embodyingmy invention.

Fig. 23 is an enlarged vertical section through the platform-support of the scale of Fig. 1 taken longitudinally of the scale.

Fig. 3 is a similar section taken at right angles to Fig. 1 and Fig. 2.

Fig. l is a plan view of this platform support. drawn on the same scale as Figs. 2 and o.

Fig. 5 is a fragi'nentary horizontal section taken through the scale along the line of Fig. 1.

Fig. 6 is an enlarged elevation of the stem which carries the platform, taken at right angles to Fig. 1, with a portion of the upper end in section.

Fig. 7 is av plan view of the lower link of the scale, also showing the pivoting connections of this link to the channel plate sup porting it and to the rack bar.

Fig. 8 is an enlarged elevation of the rear bar and the pinion engaged by the latter.

Fig. 9 is a front elevation of the casing, showing this before the pinion and dial are attached and before the rack-bar is slipped into position.

Fig. 10 is a plan view of the platform of the scale.

In the illustrated embodiment, the scale of my invention includes a sheet metal base 1 supporting an upright casing of rectangular section which is closed at its top by a slip cover 2. Extending freely through a central opening in the cover 2 is a stem t which is supported by a tension spring 5 through a pair of parallel links 6 and 7. Each of these links has at its rear end a pair of arms spaced to correspond to the dis tance between the wings 8 and 9 of a channel plate, the latter being secured to the back 3 of the casing by screws 11 which extend through the back plate and which are threaded into the back 10 of the channel plate. To prevent a loosening of these screws through the jarring of the scale, I provide the back plate 3 with a portion oiliset rearwardly from the main part of the plate but shorter and narrower than the channel plate, so that the back 10 of the latter will engage the main portion of the backof the casing tlatwise, while the said rai ed or embossed portion will be spaced by some distance from the intervening part of the back of the channel plate, after the manner shown in Figs. 1 and 5. il hen the screws 11 which extend through these spaced parts of the casing back and of the chan11el-plate back are tightened, they will flex the adjacent part of the casing back somewhat inwardly, thereby exerting a I locking effect on the screw. For the pivotal conner-tions between the wings 8 and 9 of the channel plate and the links 6 and 7, I

am here showing shafts l2 and 13 respec-- tively extending through the spaced pivot ears in these links and both extend ing tirough the said wings 8 and 9 of the channel plate. By disposing these wings 8 and 9, closely adjacent to the pivot on the two links, I prevent both lateral or twisting movement of these links with respect to the stationary channel plate and casin .io pre ent lost motion likewise between the stern a, I desirably eniploy th. arrangement shown in Figs. 6 and 7. That is to say, I provide the stem at with a relatively thin lower end portion 141- fitting betwc-en the opposed walls of a crotch fOlll'lSli tion 15 in the lower link 7 and I provide this crotch formation with a pair of pivot ears 16, so that a rivet 17 extending through the ears 16 and the said stem end 1 51; will afford the pivotal connection, while the fitting of the said stem end between the pivot ears will prevent relative lateral motion. Then I provide the stem intermediate of its ends with a pair of upwardljv' directed. cars 18 spaced to correspod to the spacin between the oppositely directed faces of a pair of pivot ears 19 on the foiwvard ends of the upper link 6. With the parts thus arranged and with the upper l nk pivoted to the stem by a shaft 20, which shaft extends loosely through a bore in the intervening part of the stem at, the spreadii'ig of the connections between the stem and the upper link cooperates with the single central connection of the stem to the lower link in preventing any rocking or tilting movement of the stem *l; transversely of the scale. Hence I can readily secure a substantially rectilinear up-and-down movement of the'stem -lwithout lost motion, while CH1- ploying an exceedingly simple construction.

To support the object to be weighed, I provide a platform, such as the one shown at 21 in Fig. 1, and I desirably secure this to the top of the stem a by simple means arranged for affording a firm connection without requiring machine work and without involving a liability to looseness or lost motion. For this purpose I preferably bevel the upper portion of the stem f from all four sides as shown in Figs.v 1 and 6. so as to afford a substantially frusto-pyramidnl u per end which will wedgingly fit into t e correspondingly shaped bore 22 of a platform-supporting bushing 23. Vith the close tit thus secured, a single screw 2% threaded through a countersunk bore in the platform 21 suffices for securing the latter to the stem l, while a widely spreading flange 25 on this platform support stitl'ens the platform. To prevent the platform from rotating about its said fastening to the stem, I desirably emboss its central portion upwardly as shown in Fig. 10 so as to lit the contour of the flange 23.

The weight of the link, stem and platform, together with that of any object supported by the platform is sustained in the usual manner by a tension spring 5 looped at its lower end through the forward arm 26 of the lower link and connected at its upper end to a threaded stem 2?. Threaded on this stem 27 is an adjusting nut 28 which engages the top of the cover 2 and by means of which the spring 5 can be raised or lowered bodily so as to bring the indicating pointer of the scale to its zero position when there is no object on the platform.

To secure the weight indication, I provide the usual dial 29 at the front of the scale and have the weight shown by a pointer 30 secured to the shaft 31 of a pin ion 32 which is engaged by a rack bar 33. the rack-bar being pivoted to the :loiwvard portion an of the lower lever. For the latter purpose, the rack-bar is desirably punched of sheet metal and has a pivot car Slitintegral with it and bent from its lovvcr end and extending at right. angles to the face of the rack-lair. or rcnrwardly of the scale so that it can be coi'inccted dire t to the lower link by a pivoting rive! 35. It) pi'oiiierty proporlioning the size of this ri et and the bores through which it extends. I can readily secure a good pivotal connection without friction or appreciable lost uiotion, thereby getting the connection between the rack and the link system without u reduction in accuracy.

In practice, I have found that a rack-bar of relatively thin sheet metal will sin-lice for this purpose and will afford greater accur cy than could be secured by a cast bar without extensive machining on the latter. However, the use of a relatively thin rackbar introduces the pmss bility that th s might jam between either end of the pinion 19 and the two plates which contine the space in which the rack-bar moves, namely the front 36 of the casing and the dial plate 29. To guard against this, I provide at least one, and preferably both. of these plates with embossed formations disposed near the pinion and directed towards the other plate, such as the annular embossed formations 37 and n8 of Fig. Such nnrmlar formations can readily be disposed fairly close to the pinion without interfering with an inexpensive assembling of the parts, and by having these forn'iations extend toward each other so that the space between them is less than the thickness of the pinion its periphery, 1 cause them to serre as guards or guides to prevent the rack-bar from engaging the main portions of the plates 36 and 29 and from jamming either behind or in front of the pinion. At the same time, I can readily guard against an undue swinging of the rack-back laterally away from the pinion by a relatively close disposing of one of the fastening screws 39 which fasten the dial plate to the casing front after the usual manner.

To permit the connecting of the rack bar to the lower link 26, I provide the front of the casing with a corresponding opening it) and I desirably make this opening of such a size that the rack-bar can readily be inserted or withdrawn through itafter the ear SA on the rack-bar has been pivotally connected to the lower link. By doing this, I can assemble almost the entire mechanism of the scale before it is introduced into the casing, namely with the two links (5 and 7 pivoted to the channel-plate and the stem 4, with this stem extending through the cover, with the spring operatively interposed between the cover and th lower link, and with the rack-bar pivoted to the lower link. Then the parts as thus assembled can be slipped into position after they have been properly adjusted and can be secured in pocition by merely attaching of the two screws 11 and tightening the adjusting nut To reduce the friction between the two parallel links and the parts to which they are pivotally connected, I preferably provide the bearing portions with contiguous boss formations through which the pivoting axles extend, so as to afford contact surfaces of quite limited area. By so doing and by desirably also convexing these bosses, 1 prevent all tendency of the mechanism to stick and I reduce the friction so as to secure a high degree of sensitivencss in a relatively cheap scale construction.

However, while I have illustrated and described the various reatures of my invention in an embodiment including certain desirable shapes of different parts, 1 do not wish to be limited to the details of the con struction and arrangement. thus disclosed, it being obvious that many changes might be made in the construction and arrangenent without departing either from the spirit of my invention or from the appended claims.

I claim as my invention in a. scale of the class described, a casing including a top provided with a per- ;im-ation, a vertically disposed stem extending freely through the perforation, a pair of parallel links disposed one above another and each pivotally connected at its opposite ends respectively to the casing and the stem, the stem having its upper end tapered to a frusto-pyramidal shape, a flange having a shank provided with an upwardly tapering bore corresponding throughout its length to the frusto-pyamidal shape of the said stem end and having the said end socketed therein, the flange having its top enlarged to form a head larger than the said per-foration, a platform seated on the said flange head, a screw extending through the platform into the said upper stem end to clamp the flange between the stem and the platform, and resilient; means for resisting the movemei'it transmitted to the stem by the load on the platform.

2. In a scale of the class described, a casin carrier plate within the casing and contiguous to a wall of the casing, a platforn'i-supporting stem extending downwardly into the casing. a pair of parallel links pivotally connecting the carrier plate with the stem, resilient means for resisting movement transmitted to the links by a load on the platform on the supporting stem, and screws securing the carrier plate to the said casing wall; the said wall having a portion of considerable area (and including the parts through which the screws extend) offset from the remainder of the wall to afford a space between th said portion and the carrier plate and to permit the said portion to be flexed toward the latter when the screws are tightened, whereby the resilicm-y of the said wall will lock the screws against loosening.

$3. In a scale of the class described, a casing, a platformeupportiug stem extending downwardly into the casing, a pair of para llel links connecting the stem with the casing, weight-indicating means including a pinion journalcd on an axis parallel to the l nks, a flat rack-bar engaging the pinion, the rack-bar having an end portion bent at. right angles to its toothed portion. and pivoted to one of the links on an axis transverse of the axis of the pinion, the part of the last nan'ied link adjacent to the said pivotal connection, to the end portion of the rack-bar having a surface disposed in flatwise engagement with the said rackbar portion so as to prevent lateral movement of the rack-bar transverse of the axis of the pinion.

-':l:. in a scale, a casing having a dial forwardly of and spaced from the front of the casing, there being an aperture in the said front, a rack-bar movable in the space between the dial and front; object-supporting mechanism including a member pivotally connected to the rack-bar and a spring interposed between the said member and the top of the casing, one of the thus pivotally coir net-ted mei'nbers having a po tion extending through the said aperture; indicating means including a pinion disposed in the said space and meshing with the raclebar and a pointer fast on the pinion and disposed in front of the dial; and guide means in the said space for holding the major portion of the rackbar away from the said front and dial.

5. A scale as per claim l, in which the guide means comprise a formation formed on one of the members spaced by the said space and extending into the said space adjacent to the pinion 6. A scale as per claim at, in which the guide means coi'nprise annular formations on the said dial and front extending towards each other concentric with and adjacent to the pinion.

7.111 a scale, objcot-supporting mecha nism including a lever and resilient means for resisting movement of the lever by the weight of the sug'iported object, and indicating means including ha d connected to a pinion, and means opera ively connecting the lever and pinion; the said means com prising a rack-bar punched from sheet metal and having its teeth meshed with the pinion and having a per orated end portion bent at right angles to its toothed portion ant dis posed in tlatwise engagement with one end of the lever, and a pivot pin extending through the perforation in the sa d end portion and through one end of the said lever.

8. In a scale, a platform, a vertical stem supporting the platform and provided intermediate its lcn ch with a pair of widely spaced hearing I and having a lower end portion in a vertical plane medial of the said bearings, a casino; a pair of links for supporting the stem from the casing, the upper link having two pairs of laterally spaced. ends respectively pivoted to the casing and to the said bearings, the lower link being of a substantially Y-shaped forn'iation with the arms thereof pivoted to the casing at laterally spaced points and having at its crotch a pair of bearings disposed respectively at opposite sides of the lower end of the stem and pivoted conjointly to the latter and resilient means for resisting the movement transniitted through the stem by a load on the platform.

9. A scale as per claim 8, in which the widely spaced hearings on the stem and the link ends adjacent thereto are provided with convexed boss formations engaging each other to afford annular engaging surfaces of quite limited area.

10. A scale as per claim 8, in which the lower end of the stem and the bearings at the crotch of the lever have interengaging boss formations contacting with one another to afford annular engaging surfaces of quite limited area.

11. In a scale of the class described, a casing, a carrier plate having a main portion secured flatwise to a wall thereof and having a pair of parallel wings extending vertically from opposite edges of the said main portion; and objectsupporting means including a vertical stem and a pair of parallel links connecting the stem with the carrier plate, each of the links having a pair of spaced ends provided with convcxed bosses l ected away from each other and respectively engaging the said wings and pivoted to the latter, whereby the said bosses afford contact surfaces of quite limited area engaging the said wings, and resilient means for resisting: a movementof the stem by a load on the object supporting means.

Signed at Chicago, Illinois, December 12th, 1924.

LELAND G. KNAPP. 

